Researchers at the Swiss Federal Institute of Technology in Zurich have developed a groundbreaking method for extracting gold from electronic circuit boards, utilizing by-products of the dairy industry, specifically whey, a liquid remaining after milk has been curdled and strained during cheese production. This novel approach not only presents a cost-effective alternative to traditional gold recovery methods but also promises high purity results, potentially transforming electronic waste recycling processes.
The technique involves denaturing whey proteins through heating, leading to the aggregation of protein amyloid fibrils into a gel. Upon drying, this gel forms an adsorbent sponge capable of effectively filtering gold from acid-treated electronic boards, a common pre-treatment process to ionize metals.
During trials, the adsorbent sponge successfully extracted gold from numerous computer motherboards, demonstrating a distinct efficiency in adhering valuable metal ions over other metals like copper and iron present in the solution. The final step involved heating the gold-ion-saturated sponge, resulting in the formation and melting of flakes to produce a gold ingot.
Chemical analysis of the ingot revealed a composition of 90.8% pure gold, with the remainder being nickel (0.018%) and copper (10.9%). This level of purity equates to approximately 22 carats in jewelry standards. Remarkably, the cost of recovering 1 gram of gold using this method is reported to be 50 times lower than traditional industrial gold extraction techniques. 
